Excess sludge reduction by biological way: From experimental experience to a real full scale application

Concerning the role of cell lysis-cryptic growth in anaerobic side-stream reactors: The single-cell analysis of viable, dead and lysed bacteria

“…Troiani et al (2011) confirmed that the endogenous decay rate was not particularly improved in the ASSR tank, while a higher decay rate was observed in the oxidation tank, but the authors highlighted the need for further research in this field.…”

“…The theoretical hydraulic retention time (HRT) in the ASSR tank was about 7 d, coinciding in practice with the sludge retention time (SRT) in the anaerobic tank, due to the scarce settleability of anaerobic sludge as a consequence of the high solids concentrations. The HRT in the ASSR tank is in the same order of magnitude of 10 d applied in other ASSR studies (Novak et al, 2007;Johnson et al, 2008;Troiani et al, 2011;Kim et al, 2012).…”

“…The values indicated in Table 2 may not immediately be comparable with the literature data on the endogenous decay rate if this parameter was measured with different methods. Troiani et al (2011) observed that different methodologies applied for measuring the decay rate may give different values and further investigation is therefore needed to understand comparison between literature data. In addition, higher decay coefficient under aerobic conditions in comparison with w a t e r r e s e a r c h 7 4 ( 2 0 1 5 ) 1 3 2 e1 4 2 anaerobic conditions was also demonstrated for ammonia oxidising bacteria (Munz et al, 2011).…”

“…Some hypotheses have been proposed in the literature to explain the possible mechanisms of sludge reduction, such as uncoupling metabolism (Chudoba et al, 1992b;Troiani et al, 2011) or cell lysiscryptic growth (Wei et al, 2003;Quan et al, 2012), but these processes have not been fully demonstrated to date. In the study of An and Chen (2008) sludge decay in the anaerobic reactor was indicated as the main mechanism of the OSA system.…”

The effect of iron dosing on reducing waste activated sludge in the oxic-settling-anoxic process

“…Observed yield is accepted as a suitable marker for the sludge reduction by researchers Wang et al, 2007;Low et al, 2000;Troiani et al, 2011;Khanthongthip et al, 2015). In this study, the observed biomass yield values were determined for slow and fast feed SBRs receiving different influent iron concentrations by using the mixed liquor solids data.…”